The attachment of the fertilized egg to the wall of the uterus marks the start of a pregnancy. But how does the process of implantation happen exactly?
How ovulation leads to fertilization
Every woman is born with millions of immature eggs that wait to be released, normally one at a time with every cycle — a process known as ovulation. After ovulation, your egg travels into one of your fallopian tubes, where it awaits the arrival of sperm. If you had intercourse on that day, or in the days leading up to ovulation, sperm would be making their way towards the egg. If one successfully penetrates the egg, fertilization occurs, and a new life begins in the form of a zygote – a single cell that contains all the genetic material needed to create a baby.
The trip to the uterus
Over the next few days, this zygote begins to divide, creating an ever-growing cluster of cells. During this time, it’s also making its way down the fallopian tube towards the uterus. By the time it reaches the uterus, usually around 3 to 4 days after fertilization, it has become a blastocyst – a tiny ball of cells.
Preparing for implantation
Once in the uterus, the blastocyst is ready to implant into the uterine wall. This can happen anywhere from 6 to 10 days after ovulation. This process, known as implantation, is where the blastocyst attaches itself to the uterine lining, setting up a home for the next nine months.
Early signs of implantation
Some women may experience mild symptoms during implantation, like light spotting, often called implantation bleeding. This isn’t like a regular menstrual period; it’s generally much lighter and lasts for a shorter time. Some women might also feel a slight cramp or twinge in their lower abdomen, often mistaken for pre-menstrual cramps.
From implantation to confirmation
Post-implantation, the blastocyst (now referred to as an embryo) signals its presence by producing the hormone human chorionic gonadotropin (hCG). This is the hormone that home pregnancy tests detect. However, it takes time for hCG levels to rise high enough to be detected, so it’s generally recommended to wait until the day of your missed period to take a pregnancy test for the most accurate results.
Understanding implantation and what could be happening in your body right now is both exciting and empowering. Keep in mind that everyone’s experience is unique, and not all women will notice the signs of implantation. If you think you might be pregnant or have any concerns, always consult with a healthcare provider.
Dr. Sirichet Anekpornwattana (Fertility doctor) (1 August 2023)